Key Diagnostic Takeaways Location & Pattern: The absolute key differentiator under the microscope is that Pyoderma Gangrenosum centers around the hair follicles (folliculocentric), whereas Sweet Syndrome forms a diffuse, continuous band across the superficial dermis. Tissue Destruction: Pyoderma Gangrenosum is highly destructive, characterized by marked epidermal undermining, pseudoepitheliomatous hyperplasia, and overt necrosis. Sweet syndrome typically retains its epidermal structure despite heavy dermal edema and neutrophilic infiltration.